I had the exact same problem, it's the RAM, what i did is take the RAM out, grab a soft clothe and start rubbing it all over, you can use your shirt, then carefully put it back in the computer, if it still doesn't work, just grab the ram again and rub it on some soft clothe again but harder.
This solved my problem and many others as well, just give that RAM a little love.
Still doesn't work? Hope it has a warranty and call the producer of the hardware and they can hand you another one for no cost.